Chair with conforming seat

Information

  • Patent Grant
  • 6811218
  • Patent Number
    6,811,218
  • Date Filed
    Tuesday, December 10, 2002
    22 years ago
  • Date Issued
    Tuesday, November 2, 2004
    20 years ago
Abstract
A task chair including a seat support structure, and a seat supported by the seat support structure and having a seating surface which may ergonomically conform to a seated user. The seating surface includes rigid and flexible portions connected to one another, the flexible portions allowing resilient flexing of the seating surface to create conformance zones which dynamically support a seated user in an ergonomic manner.
Description




BACKGROUND OF THE INVENTION




1. Field of the Invention




The present invention relates to chairs, and in particular, to a task chair for supporting a seated user thereon in an ergonomic manner.




2. Description of the Related Art




Task chairs are commonly used by persons while working in a seated position in an office or other occupational environment. Typically, such chairs include a caster wheel assembly for rolling movement over a floor surface, as well as a number of manual adjustment features to allow the user to adjust the shape or movement characteristics of the chair to a desired configuration.




Many task chairs include a rigid seat pan and a rigid backrest pan, the seat pan and backrest pan including a layer of foam padding thereon which is covered by a decorative upholstery material. Although the foam padding provides some cushioning support for a seated user, the rigid and noncompliant seat pan and backrest pan may become uncomfortable to the user, especially if the user is seated at the chair for an extended period of time. In this connection, if the layer of foam padding is too thin, the user's ischium or tail bone may abut the rigid seat pan to cause discomfort, and, if the layer of foam padding is too thick, the seat may not provide a firm overall support for the user.




Other known task chairs include seats having a relatively rigid outer frame supporting a mesh or webbing material thereacross which is flexible to conform to the seated user. However, such mesh or web material may catch, wear, or snag a user's clothing when the user shifts positions in the chair or stands up from the chair. Also, such mesh or webbing material is somewhat frictionless, such that when a user uses the forward tilt mechanism of the chair, the user experiences the sensation of falling forwardly or sliding out of the chair. Similarly, when the user moves to a reclined posture in such chairs, the user tends to slide forwardly out of the chair, and the lumbar region of the user's back disengages from the lower portion of the backrest.




What is needed is a task chair which conformingly and comfortably supports a seated user, and which is an improvement over the foregoing.




SUMMARY OF THE INVENTION




The present invention provides a task chair including a seat support structure, and a seat supported by the seat support structure having a seating surface which may ergonomically conform to a seated user. The seating surface includes rigid and flexible portions connected to one another, the flexible portions allowing resilient flexing of the seating surface to create conformance zones which dynamically support a seated user in an ergonomic manner.




The rigid portions of the seat may be formed of wood, metal, or a rigid plastic, for example, and the flexible portions may be formed of a pliable urethane or a silicone material, for example. The rigid and flexible portions may be connected to one another by insert molding the flexible portions to the rigid portions, or by mechanically or adhesively joining the flexible portions to the rigid portions. The particular shape, size, and relative configurations of the rigid portions and the flexible portions may be selectively varied to provide seating surfaces having desired conformance and support characteristics for the seated user.




The seat support structure may include a seat flex lockout mechanism movable between a first position and a second position, wherein flexing of the seating surface is prevented in the first position and is allowed in the second position. Additionally, the seat support structure may include a mechanism which allows the seat to be moved between high, middle, and low positions.




Advantageously, the present task chair includes a seating surface having rigid portions which provide a relatively firm support to a seated user, and flexible portions which facilitate movement of the flexible and rigid portions of the seating surface, and which provide support to the seated user in selected zones of the seating surface. Additionally, the flexible portions permit the seating surface to resiliently flex from a relatively planar shape to a saddle or saddle-like shape which conforms to the seated user. Further, the saddle-like shape supports the seated user, preventing the user from experiencing the sensation of falling or sliding out of the chair.




In one form thereof, the present invention provides a chair, including seat support structure; and a seat supported by the seat support structure, the seat including a flexible portion and at least one rigid portion, the seat resiliently movable between a first position in which the seat has a substantially flattened shape, and a second position in which opposite sides of a front portion of the seat are flexed downwardly about a central portion of the seat to form a saddle-like shape.




In another form thereof, the present invention provides a chair, including seat support structure; and a seat supported by the seat support structure, the seat formed of a flexible material having at least one rigid member embedded therein, the seat resiliently movable between an unflexed position and a flexed position in which opposite sides of a front portion of the seat are flexed downwardly about a central portion of the seat to provide a saddle-like shape.




In a further form thereof, the present invention provides a chair, including seat support structure including a rigid support member; and a seat supported by the seat support structure, the seat including a flexible portion disposed centrally within the seat, the flexible portion supported by the rigid support member; a rigid portion disposed along each side portion of the seat opposite the flexible portion, the seat resiliently movable between an unflexed position and a flexed position in which the side portions of the seat flex downwardly about opposite sides of the flexible portion to form a saddle-like shape.











BRIEF DESCRIPTION OF THE DRAWINGS




The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention itself will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:





FIG. 1

is a side elevational view of a task chair in accordance with the present invention;





FIG. 2

is an additional side elevational view of the task chair of

FIG. 1

, schematically showing a user seated therein;





FIG. 3

is a rear elevational view of the task chair of

FIG. 1

;





FIG. 4

is a perspective view of one embodiment of a seat for the task chair of

FIG. 1

, showing the rigid and flexible portions of the seating surface, and further showing the flexing of the seating surface between a first position shown in solid lies and a second position shown in dashed lines;





FIG. 5

is a side perspective view of a first embodiment of a seat support structure, showing the seat support structure in a high or upright position with the seat in a non-flexed shape;





FIG. 6

is side perspective view of the seat support structure of

FIG. 5

, showing the seat support structure in a high or upright position with the seat flexed in a saddle-like shape;





FIG. 7

is side perspective view of the seat support structure of

FIGS. 5 and 6

, showing the seat support structure in a low or reclined position, with the seat flexed in a saddle-like shape;





FIG. 8

is side perspective view of the seat support structure of

FIG. 5

, further showing a flex lockout mechanism disposed in a disengaged position, such that flexing of the seat allowed;





FIG. 9

is side perspective view of the seat support structure of

FIG. 8

, showing the flex lockout mechanism disposed in an engaged position, such that flexing of the seat is prevented;





FIG. 10

is a side perspective view of a second embodiment of a seat support structure, showing the seat support structure in a high or raised position with the seat flexed into a saddle-like shape;





FIG. 11

is a side perspective view of the seat support structure of

FIG. 10

, showing the seat support structure in a middle position with the seat in a non-flexed shape;





FIG. 12

is a side perspective view of the seat support structure of

FIGS. 10 and 11

, showing the seat support structure in a low or reclined position with the seat flexed into a saddle-like shape;





FIG. 13

is a side perspective view of the seat support structure of

FIGS. 10-12

, showing each of the individual positions of

FIGS. 10-12

with respect to one another;





FIG. 14

is a partial perspective view of a second embodiment of a seat, showing the rigid and flexible portions of the seating surface, and further showing the flexing of the seating surface between a first position shown in solid lies and a second position shown in dashed lines;





FIG. 15

is a is a partial perspective view of a third embodiment of a seat, showing the rigid and flexible portions of the seating surface, and further showing the flexing of the seating surface between a first position shown in solid lies and a second position shown in dashed lines;





FIG. 16

is a is a partial perspective view of a fourth embodiment of a seat, showing the rigid and flexible portions of the seating surface, and further showing the flexing of the seating surface between a first position shown in solid lies and a second position shown in dashed lines;





FIG. 17A

is a is a partial perspective view of a fifth embodiment of a seat, showing the rigid and flexible portions of the seating surface, and further showing the flexing of the seating surface between a first position shown in solid lies and a second position shown in dashed lines; and





FIG. 17B

is a front elevational view of the seat of

FIG. 17A

, showing the seating surface in a saddle-like shape.











Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate preferred embodiments of the invention, and such exemplifications are not to be construed as limiting the scope of the invention in any manner.




DETAILED DESCRIPTION




Task chair


20


is shown in

FIGS. 1-3

, and generally includes seat portion


22


, backrest portion


24


, and seat support structure


26


. Seat support structure


26


includes caster wheel assembly


32


having a plurality of arms


34


projecting radially outwardly of central hub


36


, the terminal ends of arms


34


having caster wheels


38


pivotally mounted thereon. Supported within central hub


36


of caster wheel assembly


32


is a height-adjustable pneumatic cylinder


40


. Cylinder


40


includes piston


42


slidably disposed therein, an upper end of which is attached to chair support beam


44


by a press fit or in another suitable manner.




A plurality of links


46


(only two of which are shown in

FIGS. 1 and 2

for clarity) each include first ends


48


pivotally attached to chair support beam


44


and second ends


50


pivotally attached to seat support member


52


. Referring to

FIG. 3

, seat support member


52


is connected to U-shaped arm support


54


having upper ends


56


to which a pair of adjustable or fixed armrests


58


are connected. Armrests


58


may include moveable armrest pads


60


, which may be adjusted as desired by a user. Also attached to upper ends


56


of U-shaped arm support


54


are a pair of L-shaped brackets


62


including lower ends


64


supporting chair seat


70


, and upper ends


66


pivotally attached to U-shaped arm support


54


. Backrest frame


68


extends between and is moveably mounted to upper ends


66


of the two L-shaped brackets


62


and arm support


54


. Backrest frame


68


is connected to and supports backrest


72


in a manner such as that described in U.S. Provisional Patent Application Serial No. 60/340,673, entitled CHAIR WITH LUMBAR SUPPORT AND CONFORMING BACK, filed Dec. 14, 2001, assigned to the assignee of the present invention, the disclosure of which is incorporated herein by reference. Backrest


72


may further include one or more features such as those described in the above-incorporated U.S. Provisional Patent Application Serial No. 60/340,673.




Referring to

FIG. 4

, a first embodiment of seat


70


is shown. Seat


70




a


includes seating surface


76




a


defined by a rigid portion and a flexible portion, which are designated as


80




a


and


90




a


, respectively, in the embodiment of FIG.


4


. Rigid portion


80




a


is generally U-shaped, with base section


82




a


and a pair of arm sections


84




a


extending therefrom toward the front of seat


70




a


. Flexible portion


90




a


is disposed around the periphery of rigid portion


80




a


and between arm sections


84




a


thereof. Control knobs


88


may be integrated into the profile of seat


70




a


for adjusting various adjustment features of chair


20


.




The rigid portion of seat


70


may be made from any suitable substantially rigid material, such as wood, metal, or a stiff plastic material, for example. Suitable wood materials for the rigid portion include, for example, a 9-ply, gumwood, upholstery grade plywood or a rotary cut maple veneer shell.




The flexible portion of seat


70


may be made from an elastomeric material, such as a urethane or a silicone material, for example. Such material may have one or more of a shore hardness ranging from 37±7A to 82±7A, a tensile strength ranging from 505 PSI to 2200 PSI as determined by ASTM D-412, and an elongation of 320% to 340% as determined by ASTM D-368. Suitable urethane materials for the flexible portion include Vantico brand polyurethanes, available from Ciba Specialty Chemicals, such as RP6400-1, RP6401-1, RP 6402-1, and RP 6410-1 polyurethanes. The thickness of the flexible portion may be uniform throughout the seat, or alternatively, the thickness of the flexible portion may be varied as desired. The flexibility of the flexible portion generally decreases with increasing material thickness. Conversely, the flexibility of the flexible portion generally increases with decreasing material thickness.




In each of the embodiments of the seats disclosed herein, the flexible portion of the seat is resiliently flexible, such that the flexible portion may flex or bend to change shape in response to a force or load exerted thereon, followed by return of the flexible portion to its original shape or position when the force or load is removed. The material of the flexible portion may also exhibit elasticity, wherein the material may stretch as necessary responsive to forces exerted thereon, followed by return to its original shape and position. Further, the flexible portion may optionally include a series of perforations, a series of ridges and valleys, scoring, or other features therein which facilitate flexing movement in designated areas of the flexible portion.




The flexible portion of seat


70


is attached to one or more rigid portions thereof by insert molding, wherein the rigid portion is placed in a mold, and the flexible portion is molded therearound such that, upon curing, the flexible portion surrounds the periphery of the rigid portion and is securely adhered to the rigid portion. For example, if the rigid portion is made of wood or another porous or semi-porous material having roughened surfaces, the flexible portion may penetrate within the interstices of the rigid portion and, upon curing, form a tight bond with same.




Another molding process which may be used to form seat


70


is performed according to a two-step molding procedure, sometimes referred to in the art as a “two-shot” molding process. First, the rigid portions are formed from a first plastic material which is substantially rigid upon curing. The first material is injected into one or more molds which correspond to the shape of the rigid portions of the seat. Then, before the material of the rigid portions is fully cured, the flexible material is injected around the rigid portions into a mold which corresponds to the shape of the seat. The flexible material forms a chemical bond with the partially cured rigid material to provide a very strong connection between the rigid and flexible portions of the seat. After the flexible and rigid materials cure, the mold is removed to provide the seat.




The rigid portion is at least partially embedded within the flexible portion such that the flexible portion surrounds the outer periphery of the rigid portion. The top and bottom surfaces of the rigid portion may be exposed, or alternatively, the rigid portion may be completely embedded or encapsulated within the flexible portion such that the flexible portion encompasses all sides of the rigid portion.




Further, as shown in

FIG. 4

, the rigid portion


80




a


may include cavities (not shown) which communicate with holes


78


therein into which flexible portion


90




a


fills during molding to further anchor flexible portion


90




a


to rigid portion


80




a


. Alternatively, the flexible portion may be pre-molded, wherein after curing thereof, the flexible portion is mechanically joined to the rigid portion by a suitable adhesive or by suitable fasteners, for example.




Seating surface


76




a


is shown in

FIG. 4

in a first position in solid lines. In this first position, seating surface


76




a


is generally flattened or planar in overall shape, but may have some inherent contour therein based upon the shapes of rigid portion


80




a


and/or flexible portion


90




a


. For example, seating surface


76




a


may be slightly curved upwardly at the opposite side edges thereof, the front edge of seating surface


76




a


may be slightly curved downwardly, or the rear edge of seating surface


76




a


may be slightly curved upwardly.




Seating surface


76




a


is shown in

FIG. 4

in a second position in solid lines, in which seating surface


76




a


is flexed or elastically moved into a saddle or saddle-like shape. In this position, the central area of seating surface


76




a


, toward the front of seat


70


, is supported by seat support member


52


. Additionally, the rear side portions of seating surface


76




a


are supported in a suitable manner, such as by L-shaped seat support brackets


62


(FIG.


3


). Therefore, seating surface


76




a


is more firmly supported in the forward central portion of the seat and on the sides in the rear of the seat to provide a relatively firm support for the buttocks of a seated user. However, the front side portions


91




a


of seating surface


76




a


, when same are not supported by seat support structure


26


, may flex downwardly about each side of seat support member


52


under the weight of the thighs of a seated user, such that the central front portion of seating surface


76




a


, which is supported by seat support member


52


, forms a protuberance


93




a


which is disposed between front side portions


91




a


of seating surface


76




a


. Flexible portion


90




a


may stretch as necessary in the area of seat support member


52


to accommodate downward movement of front side portions


91




a.






When a seated user leans rearwardly in the chair, the weight of the user is distributed to a greater extent through the user's buttocks to the rear portion of seating surface


76




a


than through the user's thighs to the front portion of seating surface


76




a


, and therefore, front side portions


91




a


flex downwardly about seat support member


52


to a limited extent, or not at all. However, when the user leans forwardly in the chair, the weight of the user is distributed to a greater extent through the user's thighs to the front portion of seating surface


76




a


than through the user's buttocks to the rear portion of seating surface


76




a


, and therefore, front side portions


91




a


may flex further downwardly about seat support member


52


.




The saddle-like shape of seating surface


76




a


provides a flexible, conforming, ergonomic support for the seated user. The protuberance


93




a


formed in the front, central portion of seating surface


76




a


by the flexing of front side portions


91




a


downwardly about seat support member


52


is disposed between the thighs of the seated user, and prevents the seated user from experiencing the sensation of failing or sliding forwardly out of the chair. In addition, seating surface


76




a


supports the seated user when the chair is disposed in either an upright or reclined position, as described further below. Notably, seating surfaces


76




b


(FIG.


14


),


76




c


(FIG.


15


),


76




d


(FIG.


16


), and


76




e


(

FIGS. 17A and 17B

) are also resiliently moveable into a saddle-like shape to support a seated user as described above with respect to seating surface


76




a.






A first embodiment of seat support structure


26


is shown in

FIGS. 5-7

. Seat support structure


26




a


includes lower housing


100


, which is mounted to the upper end of piston


42


of pneumatic cylinder


40


(FIGS.


1


-


3


). Upper housing


102


is pivotally attached to lower housing


100


at central pivot


104


. Rear end


108


of seat support member


52


and the rigid portion of seat


70


are each pivotally attached to upper housing


102


at rear pivot


106


. Forward end


110


of seat support member


52


supports the flexible portion


90


of seat


70


thereon. Seat support member


52


further includes recess


112


in abutment with stop pin


114


secured to lower housing


100


.




In

FIG. 5

, seat


70


is shown in a position in which seat


70


is either unoccupied by a user, or in which seat


70


is occupied by a user with the flexing of seat


70


prevented or “locked out” by a flex lockout mechanism, which is described below. In the position shown in

FIG. 5

, seat


70


is disposed in a relatively planar orientation in which seat


70


is not ergonomically flexed into a saddle-like shape.




Seat


70


is shown in a saddle-like shape in FIG.


6


. In this position, the flex lockout mechanism is disengaged such that flexing of seat


70


from the substantially planar position shown in

FIG. 5

to the saddle-shaped position is permitted. Specifically, when a user sits in seat


70


, the user's thighs shift downwardly, causing the rigid portion of seat


70


to pivot about rear pivot


106


and the flexible portion


90


of seat


70


to flex downwardly about seat support member


52


. The saddle-like shape of seat


70


supports the user in a conforming, ergonomic manner, preventing the user from experiencing the sensation of falling forwardly or sliding out of the chair, as described above.




In each of the positions shown in

FIGS. 5 and 6

, a spring (not shown) operably connected between lower housing


100


and upper housing


102


biases the rear portion of upper housing


102


upwardly from lower housing


100


about central pivot


104


such that stop catch


116


of upper housing


102


abuts upper edge


118


of lower housing


100


. The respective abutments between stop catch


116


of upper housing


102


and upper edge


116


of lower housing


100


, and between recess


112


of seat support member


52


and stop pin


114


of lower housing


100


, prevent upper housing


102


and seat support member


52


from tilting forwardly from the position shown in

FIGS. 5 and 6

.




Seat support structure


26




a


is shown in a reclined or low position in

FIG. 7

, in which the weight of a user leaning backwardly in seat


70


overcomes the bias force of the spring between lower housing


100


and upper housing


102


, and upper housing


102


pivots rearwardly and downwardly about central pivot


104


with respect to lower housing


100


. As seat


70


is so reclined, stop catch


116


of upper housing


102


moves out of engagement with upper edge


118


of lower housing


100


, and seat support member


52


slides with respect to lower housing


102


such that recess


112


of seat support member


52


moves out of abutment with stop pin


114


of lower housing


100


.




Further, in the position shown in

FIG. 7

, the flex lockout mechanism is disengaged, such that flexing of seat


70


is allowed, helping to prevent slide-out of the seated user, as described above.




Also, support structure


26




a


may be reclined by the user from the position shown in

FIG. 5

even when the flexing of seat


70


is prevented by engagement of the flex lockout mechanism. Specifically, during the operation of seat support structure


26




a


as shown in

FIGS. 5-7

, the flexing of seat


70


is either prevented or allowed by the flex lockout mechanism regardless of whether seat support structure


26




a


is in an upright or in a reclined position. Conversely, the reclining of seat support structure


26




a


is determined by the positioning of the weight of the user, and is not dependent upon whether seat


70


is in a substantially planar or in a flexed position. Thus, the flexing of seat


70


and the upright/reclined positioning of seat support structure


26




a


operate independently of one another.




One suitable flex lockout mechanism


120


for seat support structure


26




a


is shown in

FIGS. 8 and 9

, and may include an actuation member such as adjustment knob


92


(FIG.


3


), for example, attached to rod


94


for moving flex lockout mechanism


120


between the disengaged position shown in FIG.


8


and the engaged position shown in FIG.


9


. Seat support cams


122


are attached to rod


94


, and contact the undersides of a suitable portion of seat


70


, such as arm sections


84




a


of the rigid portion


80




a


of seat


70




a


, for example. In the disengaged position shown in

FIG. 8

, seat support cams


122


are shifted away from the underside of seat


70


, thereby permitting the flexible portion of seat


70


to flex about seat support member


52


. The actuation member, such as adjustment knob


92


, may be turned to rotate rod


94


and seat support cams


122


to the engaged position shown in

FIG. 9

, in which seat support cams


122


are disposed beneath and contact the underside of seat


70


, preventing the flexible portion


90


of seat


70


from flexing about seat support member


52


.




A second embodiment of seat support structure


26


is shown in

FIGS. 10-13

. Seat support structure


26




b


includes chair support beam


44


mounted to the upper end of piston


42


(

FIGS. 1-3

) of pneumatic cylinder


40


. A plurality of links


46




a


,


46




b


(only two of which are visible in

FIGS. 10-13

) each include first ends


48


pivotally attached to chair support beam


44


and second ends


50


pivotally attached to seat support member


52


. Second end


50


of link


46




a


is attached to axle


123


, which is slidably received within slot


124


of seat support member


52


. Seat support member


52


, links


46




a


,


46




b


, and chair support beam


44


together may form a four bar pivot structure, as described in further detail below.




Upper ends


56


of U-shaped arm support


54


and upper ends


66


of L-shaped brackets


62


(

FIG. 3

) are pivotally attached to one another at main pivot


128


. Specifically, upper ends


66


of L-shaped brackets


62


are pivotally mounted to upper ends


56


of arm support


54


at main pivot


128


, and arm support


54


extends transversely under seat


70


, as shown in

FIG. 3

, and is rigidly connected to seat support member


52


. Upper ends


66


of L-shaped brackets


62


are pivotally mounted at main pivot


128


, and lower ends


64


of L-shaped brackets


62


support seat


70


. Tension element


74


, shown as a tension spring, for example, is attached between chair support beam


44


and chair support member


52


. Alternatively, tension element


74


may be a tension band, as shown in

FIGS. 1 and 2

, which is made from a heavy, yet stretchable, rubber material.




Tension element


74


biases seat support structure


26




b


upwardly to the high position shown in

FIG. 10

when a user is not seated within chair


20


. When a user is seated in chair


20


, tension element


74


begins to stretch, lowering seat support structure


26




b


to the middle position shown in

FIG. 11

, or to any intermediate position between the positions shown in

FIGS. 10 and 12

, depending upon the such factors as the weight of the user, the position of the user's center of gravity, the angle of the backrest, and the resistance to stretching of tension element


74


.





FIG. 10

shows seat


70


in a saddle-like shape which is attained when the user releases the flex lockout mechanism of seat


70


, such as that shown in

FIGS. 8 and 9

. Specifically, the weight of the user's legs shifts the user's thighs downwardly and causes seat


70


and upper ends


66


of L-shaped brackets


62


to pivot about main pivot


128


to a forward tilt position, and flexible portion of seat


70


to flex downwardly about seat support member


52


.




When a position lock (not shown) is released, links


46




a


,


46




b


and upper ends


66


of L-shaped brackets


62


pivot such that seat support member


52


is raised from the middle position shown in

FIG. 11

to the position shown in FIG.


10


. In

FIG. 10

, the flex lockout mechanism is disengaged, such that flexing of seat


70


from the substantially planar position shown in

FIG. 11

to the saddle-shaped position is permitted. As described above, the saddle-like shape of seat


70


supports the user in a conforming, ergonomic manner, preventing the user from experiencing the sensation of falling forwardly or sliding out of the chair


20


.




In

FIG. 11

, seat support structure


26




b


is shown in a middle position, in which seat


70


is occupied by a user with the flexing of seat


70


prevented or “locked out” by the flex lockout mechanism. Thus, in the position shown in

FIG. 11

, seat


70


is disposed in a relatively planar orientation in which seat


70


is not ergonomically flexed into a saddle-like shape.




Seat support structure


26




b


is shown in a low or reclined position in

FIG. 12

, in which the weight of a user leaning backwardly in seat


70


shifts the user's torso weight still further rearward to further overcome the bias force of tension element


74


. U-shaped arm support


54


and seat support member


52


shift downwardly, and upper ends


66


of L-shaped brackets


62


pivot about main pivot


128


. Additionally, as may be seen most clearly in

FIG. 13

, block


125


on the underside of seat support member


52


contacts link


46




a


when seat support structure


26




b


is in a middle position. When seat support structure


26




b


is moved from the middle position to the low/reclined position, block


125


pushes against link


46




a


, causing slot


124


of seat support member


52


to slide relative to (or around) axle


123


, permitting seat support member


52


to recline.




Further, in the low position shown in

FIG. 12

, the flex lockout mechanism is disengaged, such that flexing of seat


70


is allowed even when seat support structure


26




b


is in a low/reclined position, preventing the user from sliding forward in seat


70


and from disengaging his/her lumbar region from the backrest of chair


20


.




The above-described high, middle, and low positions of seat support structure


26




b


are each shown in

FIG. 13

in relation to one another, wherein tension element


74


has been omitted for clarity.




Also, seat support structure


26




b


may be raised or lowered by the user from the position shown in

FIG. 11

even when the flexing of seat


70


is prevented by engagement of the flex lockout mechanism. In this connection, during the operation of seat support structure


26




b


as shown in

FIGS. 10-13

, the flexing of seat


70


is either prevented or allowed by the flex lockout mechanism regardless of whether seat


70


is in a high (FIG.


10


), middle (

FIG. 11

) or low (

FIG. 12

) position. Conversely, the high position and low position of seat support structure


26




b


is determined by the positioning of the weight of the user, and is not dependent upon whether seat


70


is in a substantially planar or in a flexed position. Thus, the flexing of seat


70


and the raising or lowering of seat support structure


26




b


operate independently of one another.




In each of the embodiments disclosed herein, at least a portion of the seat support member


52


of seat support structure


26


supports the front central region of seat


70


. Seat support member


52


, or a portion thereof, may be pivotally attached to the remainder of seat support structure


26


to enable seat support member


52


to remain in supporting contact with the underside of seat


70


throughout movement of seat support structure


26


between high and low positions.




As discussed below, and regardless of the type of seat support structure


26


which is employed in chair


20


, the shapes and relative configurations of the rigid portions and the flexible portions of seat


70


may be varied substantially in order to selectively modify the nature of the support provided by the rigid portions and the flexible portions, as well as the dynamics of the flexing of the seating surface of seat


70


. The embodiments of

FIGS. 14-17B

illustrate some possible shapes and relative configurations of the rigid portions and the flexible portions, although one of ordinary skill in the art may develop others based upon the teachings herein.




A first additional embodiment of seat


70


is shown in FIG.


14


. Seat


70




b


includes seating surface


76




b


formed by rigid portion


80




b


and flexible portion


90




b


. Rigid portion


80




b


is generally U-shaped, and includes base section


82




b


and arm sections


84




b


extending therefrom. Rigid portion


80




b


also includes a substantially oval-shaped cutout portion


96


. Flexible portion


90




b


is disposed around the outer periphery of rigid portion


80




b


, between arm sections


84




b


, and within cutout portion


96


. The area of flexible portion


90




b


within cutout portion


96


provides a relief area


98


which is disposed beneath the ischium of a seated user to provide flexible, cushioning support thereto. Seating surface


76




b


of


70




b


may flex about seat support member


52


in a manner similar to that of seat


70




a


between a generally planar shape (shown in solid lines) and a saddle-like shape (shown in dashed lines) in which front side portions


91




b


flex downwardly about seat support member


52


to form protuberance


93




b


. Flexible portion


90




b


may stretch as necessary in the area of seat support member


52


to accommodate downward movement of front side portions


91




b


. When seating surface


76




b


is flexed to the saddle-like shape, arm sections


84




b


of rigid portion


80




b


and flexible portion


90




b


provide a flexible support for a seated user's thighs, while base section


82




b


of rigid portion


80




b


provides a more rigid support.




In

FIG. 15

, another embodiment of seat


70


is shown. Chair seat


70




c


includes seating surface


76




c


formed by rigid portion


80




c


and flexible portion


90




c


. Rigid portion


80




c


includes base section


82




c


and a central, single forwardly projecting arm


84




c


about which flexible portion


90




c


may flex between a generally planar position (shown in solid lines) and a saddle-like-shaped position (shown in dashed lines) in which front side portions


91




c


flex downwardly about seat support member


52


to form protuberance


93




c


. Flexible portion


90




c


may stretch as necessary in the area of seat support member


52


to accommodate downward movement of front side portions


91




c


. Thus, in the embodiment shown in

FIG. 15

, a flexible support is provided for the thighs of a seated user by flexible portion


90




c


, and a more rigid support is provided by rigid portion


80




c.






A further embodiment of seat


70


shown in FIG.


16


. Chair seat


70




d


includes seating surface


76




d


formed by rigid portion


80




d


and flexible portion


90




d


. Rigid portion


80




d


is disposed in the rear portion of seat


70




d


, and flexible portion


90




d


is disposed in the front portion of seat


70




d


and around the periphery of rigid portion


80




d


. Flexible portion


90




d


may flex about seat support member


52


between a generally planar position (shown in solid lines) and a saddle-like-shaped position (shown in dashed lines) in which front side portions


91




d


flex downwardly about seat support member


52


to form protuberance


93




d


. Flexible portion


90




d


may stretch as necessary in the area of seat support member


52


to accommodate downward movement of front side portions


91




d


. Thus, in the embodiment shown in

FIG. 16

, a flexible support is provided for the thighs of a seated user by flexible portion


90




d


, and a more rigid support is provided by rigid portion


80




d.






A further embodiment of seat


70


shown in

FIGS. 17A and 17B

. Chair seat


70




e


includes seating surface


76




e


formed by rigid portions


80




e


and flexible portion


90




e


. Rigid portions


80




e


are disposed along the sides of seat


70




d


, and flexible portion


90




e


is disposed between rigid portions


80




e


and around the outer peripheries of rigid portions


80




e


. In a first position, shown in solid lines in

FIG. 17A

, seating surface


76




e


has a generally flattened or planar overall shape, but may include some inherent contour therein, such as downward curvature at the front edge of seating surface


76




e


, for example.




Seating surface


76




e


is elastically movable to a second, saddle-shaped form, which is shown in dashed lines in FIG.


17


A and is further shown in FIG.


17


B. In this position, flexible portion


90




e


flexes about seat support member


52


, with front side portions


91




e


of seating surface flexing downwardly under the weight of the thighs of a seated user. Flexible portion


90




e


may stretch as necessary in the area of seat support member


52


to accommodate downward movement of front side portions


91




e


. Front side portions


91




e


will generally flex downwardly about seat support member


52


to a lesser extent (or not at all), when the seated user leans backwardly against backrest


72


and shifts more weight to the user's buttocks, which weight is transferred to the chair through the rear portion of seating surface


76




e


which is supported by L-shaped seat support brackets (FIG.


17


B). Conversely, front side portions


91




e


of seat support surface


76




e


will generally flex downwardly about seat support member


52


to a greater extent when the seated user leans forwardly away from backrest


72


and shifts more weight to the front portion of seating surface


76




e


, which weight is transferred to the chair through the user's thighs. In this position, the front portion of seat support member


52


supports flexible portion


90




e


of seating surface


76




e


between front side portions


91




e


, and forms a protuberance


93




e


(

FIG. 17B

) between front side portions


91




e


at the front of seat support surface


76




e


. This protuberance


93




e


is disposed between the thighs of a seated user and prevents the user from experiencing the sensation of sliding forwardly out of the chair.




Notably, in the embodiment of

FIGS. 17A and 17B

, as well as in each of the other embodiments disclosed herein, front side portions


91




a-e


of seat support surfaces


76




a-e


may flex downwardly about seat support member


52


under the weight of a user's thighs either concurrently, or independently of one another. For example, if a user leans forwardly and evenly upon a seat support surface


76




a-e


, transferring the user's weight to the seat support surface


76




a-e


evenly through each of the user's thighs, both of the front side portions


91




a-e


of the seat support surface


76




a-e


will flex downwardly about seat support member


52


to the same extent. However, if a user leans forwardly and to one side upon the seat support surface


76




a-e


, transferring the user's weight to the seat support surface


76




a-e


more through one of the user's thighs than the other, one side portion


91




a-e


will flex downwardly to a greater extent than the other side portion


91




a-e


. In this manner, side portions


91




a-e


of seat support surfaces


76




a-e


may flex downwardly about seat support member


52


together, independently of one another, or to mutually varying extents with respect to one another, depending upon the distribution of the user's weight on the seat support surface


76




a-e.






Additionally, a further embodiment (not shown) of seat


70


may include a rigid portion shaped similarly to rigid portions


80




a-e


of seats


70




a-e


shown in FIGS.


4


and


14


-


17


B, respectively, for example. The rigid portion is fully encapsulated in a flexible portion which is molded around the rigid portion to provide a desired seat shape, wherein such seat may exhibit flexing and conformance characteristics similar to seats


70




a-e


shown in FIGS.


4


and


14


-


7


B.




While this invention has been described as having preferred designs, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.



Claims
  • 1. A chair, comprising:seat support structure including a support member; and a seat formed of a flexible material, said seat comprising: a central front portion positioned upon and supported by said support member; and a pair of side portions, each side portion including at least one rigid member connected to said flexible material and supported by said seat support structure, said seat resiliently flexible responsive to the weight of a seated user between a first position in which said seat has a generally flat shape, and a second position in which said side portions are flexed downwardly about said support member beneath said central front portion of said seat to form a saddle shape.
  • 2. The chair of claim 1, wherein said flexible material is an elastomeric material.
  • 3. The chair of claim 2, wherein said elastomeric material is one of a flexible urethane material and a flexible silicone material.
  • 4. The chair of claim 1, wherein said rigid members are embedded within said flexible material, said flexible material at least partially surrounding said rigid members.
  • 5. The chair of claim 1, wherein said rigid members are made from one of a metal, a rigid plastic material, and wood.
  • 6. The chair of claim 1, wherein said flexible material occupies an area of said seat which is normally disposed beneath the ischium of a seated user.
  • 7. The chair of claim 1, wherein said side portions of said seat are independently flexible with respect to one another between said first and second positions responsive to the weight of a seated user.
  • 8. The chair of claim 1, wherein said seat support structure includes a pair of uprights disposed on opposite sides of said seat, and a backrest pivotally connected to said uprights.
  • 9. A chair, comprising:seat support structure; and a seat supported by said seat support structure, said seat having a central front portion disposed between a pair of opposite side portions, said seat formed of an elastically flexible material having at least one rigid member embedded within said flexible material, said seat resiliently movable responsive to the weight of a seated user between a first, unflexed position and a second, flexed position in which said opposite side portions of said seat are flexed downwardly about said central front portion of said seat to provide a saddle shape.
  • 10. The chair of claim 9, wherein said seat support structure comprises a rigid support member disposed centrally beneath said seat, said rigid support member engaging said central front portion of said seat, wherein said opposite side portions of said seat may flex about said rigid support member between said first and second positions.
  • 11. The chair of claim 9, wherein said flexible material is an elastomeric material, said material molded around each of said rigid members.
  • 12. The chair of claim 11, wherein said elastomeric material is one of a flexible urethane material and a flexible silicone material.
  • 13. The chair of claim 9, comprising a pair of said rigid members respectively embedded within said side portions of said seat.
  • 14. The chair of claim 9, wherein said side portions of said seat are independently flexible with respect to one another between said first and second positions responsive to the weight of a seated user.
  • 15. The chair of claim 9, wherein said flexible material occupies an area of said seat which is normally disposed beneath the ischium of a seated user.
  • 16. The chair of claim 9, wherein said seat support structure includes a pair of uprights disposed on opposite sides of said seat, and a backrest pivotally connected to said uprights.
  • 17. A chair, comprising:seat support structure including a support member; and a seat supported by said seat support structure, said seat comprising: a flexible central portion positioned upon and supported by said support member; a pair of opposite flexible side portions, each said side portion including a rigid member embedded therein, said seat elastically movable between a first, unflexed position in which said seat has a generally flat shape and a second, flexed position in which said side portions of said seat are flexed downwardly about said support member to form a saddle shape.
  • 18. The chair of claim 17, wherein said flexible central and side portions are made of an elastomeric material.
  • 19. The chair of wherein said elastomeric material is one of a flexible urethane material and a flexible silicone material.
  • 20. The chair of claim 17, wherein said flexible central portion occupies an area of said seat which is normally disposed beneath the ischium of seated a user.
  • 21. The chair of claim 17, wherein said seat support structure includes a pair of uprights disposed on opposite sides of said seat, and a backrest pivotally connected to said uprights.
  • 22. The chair of claim 17, wherein said side portions of said seat are independently flexible with respect to one another between said first and second positions responsive to the weight of a seated user.
  • 23. A chair, comprising:seat support structure including a support member; and a seat formed of a flexible material, comprising: a pair of opposite rear side portions each connected to said seat support structure; a pair of front side portions; and a front central portion disposed between said front side portions, said front central portion positioned upon and engaging said support member, said seat resiliently flexible responsive to the weight of a seated user between a first position in which said seat has a generally flat shape, and a second position in which said front side portions of said seat are flexed downwardly about said support member to form a saddle shape, said opposite front side portions of said seat independently flexible with respect to one another responsive to the weight of a seated user.
  • 24. The chair of claim 23, wherein said flexible material is an elastomeric material.
  • 25. The chair of claim 24, wherein said elastomeric material is one of a flexible urethane material and a flexible silicone material.
  • 26. The chair of claim 23, wherein said seal further includes at least one rigid portion embedded within said flexible material.
  • 27. The chair of claim 23, wherein said seat support structure includes a pair of uprights disposed on opposite sides of said seat, and a backrest pivotally connected to said uprights.
  • 28. The chair of claim 1, wherein wherein said seat further comprises a rear portion including said rigid member, said rigid member including a cutout positioned in an area of said seat which is normally disposed beneath the ischium of a seated user, said flexible material at least partially filling said cutout.
  • 29. The chair of claim 1, wherein said seat support structure comprises a flex lockout mechanism, said flex lockout mechanism, said flex lockout mechanism moveable between a first position in which said lockout mechanism prevents flexing of said seat and a second position in which said lockout mechanism permits flexing of said seat.
  • 30. The chair of claim 1, wherein said seat support structure includes a caster wheel assembly having a height-adjustable pneumatic cylinder extending upwardly therefrom, said cylinder including an upper end operably supporting said seat.
  • 31. The chair of claim 9, wherein said seat support structure comprises a flex lockout mechanism, said flex lockout mechanism moveable between a first position in which said lockout mechanism prevents flexing of said seat and a second position in which said lockout mechanism permits flexing of said seat.
  • 32. The chair of claim 17, wherein said seat support structure comprises a flex lockout mechanism, said flex lockout mechanism moveable between a first position in which said lockout mechanism prevents flexing of said seat and a second position in which said lockout mechanism permits flexing of said seat.
  • 33. The chair of claim 23, wherein said seat support structure comprises a flex lockout mechanism, said flex lockout mechanism moveable between a first position in which said lockout mechanism prevents flexing of said and a second position in which said lockout mechanism permits flexing of said seat.
CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under Title 35, U.S.C. §119(e) of U.S. Provisional Patent Application Ser. No. 60/340,570, entitled CHAIR WITH CONFORMING SEAT, filed on Dec. 14, 2001.

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Provisional Applications (1)
Number Date Country
60/340570 Dec 2001 US